Since Dave is now an EMT and is trained to think on his feet, making a quick assessment of a life and death situation, did he walk into 5150 and go into EMT mode? I'm sure Dave's been in many a crackhouse in NYC saving lives, so did 5150 resemble a crackhouse with Ed as the main crackhead?
I can picture Dave coming in and calling for an ambulance to come get Eddie before Eddie overdosed. Maybe Dave saved Eddie's life and sent him to rehab? Anybody?
Hell, I can even see Ed threatening the EMT while they were pushing his ass into the ambulance with a kick to the crotch.